Current sensor package with continuous insulation

ABSTRACT

A current sensor package, comprises a current path and a sensing device. The sensing device is spaced from the current path, and the sensing device is configured for sensing a magnetic field generated by a current flowing through the current path. Further, the sensing device comprises a sensor element. The sensing device is electrically connected to a conductive trace. An encapsulant extends continuously between the current path and the sensing device.

CROSS-REFERENCE TO RELATED APPLICATION

This Utility Patent Application claims priority to German PatentApplication No. 10 2018 114 426.1, filed Jun. 15, 2018, which isincorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to current sensor packages and methods ofmanufacturing a current sensor package.

Description of the Related Art

Packages may be denoted as encapsulated electronic chips with electricalconnects extending out of the encapsulant and being mounted to anelectronic periphery, for instance on a printed circuit board.

Magnetic current sensors, i.e. current sensors sensing a magnetic fieldgenerated by the current to be measured, provide for contactlessmeasurement of the current and allow galvanic separation of the currentto be measured and the sensor.

Packaging cost is an important driver for the industry. Related withthis are performance, dimensions and reliability. The differentpackaging solutions are manifold and have to address the needs of theparticular application.

DE 11 2012 003 079 T5 discloses a current sensor packaged in anintegrated circuit package to include a magnetic field sensing circuit,a current conductor and an insulator that meets the safety isolationrequirements for reinforced insulation under the UL 60950-1 Standard ispresented. The insulator is provided as an insulation structure havingat least two layers of thin sheet material. The insulation structure isdimensioned so that plastic material forming a molded plastic body ofthe package provides a reinforced insulation. According to oneembodiment, the insulation structure has two layers of insulating tape.Each insulating tape layer includes a polyimide film and adhesive. Theinsulation structure and the molded plastic body can be constructed toachieve at least a 500 VRMS working voltage rating.

For these and other reasons, there is a need for the present sensorpackage and method.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of exemplary embodiments and constitute a part of thespecification, illustrate exemplary embodiments of the herein disclosedsubject matter.

In the drawings:

FIG. 1 illustrates a cross-sectional view of a current sensor packageaccording to embodiments of the herein disclosed subject matter.

FIG. 2 illustrates a cross-sectional view of a further current sensorpackage according to embodiments of the herein disclosed subject matter.

FIG. 3 illustrates some isolation aspects according to embodiments ofthe herein disclosed subject matter for the current sensor package ofFIG. 1.

FIG. 4 illustrates a cross-sectional view of a further current sensorpackage according to embodiments of the herein disclosed subject matter.

FIG. 5 to FIG. 10 illustrate different geometries of a current path(e.g. a current rail) according to embodiments of the herein disclosedsubject matter.

FIG. 11 shows the exemplary second geometry of the current path of FIG.6 and illustrates a possible location for two Hall sensors.

FIG. 12 shows the exemplary second geometry of the current path of FIG.6 and illustrates a possible location for two magnetoresistance sensors.

FIG. 13 illustrates a leadframe according to embodiments of the hereindisclosed subject matter.

DETAILED DESCRIPTION

There may be a need to manufacture a current sensor package with a highlevel of reliability.

According to a first aspect of the herein disclosed subject matter, acurrent sensor package is provided.

According to an embodiment, the current sensor package comprises acurrent path; a sensing device (e.g. a sensor chip), the sensing devicebeing spaced from the current path, and the sensing device beingconfigured for sensing a magnetic field generated by a current flowingthrough the current path; the sensing device comprising a sensorelement, the sensing device being electrically connected to a conductivetrace; the current sensor package further comprising an encapsulantextending continuously between the current path and the sensing device.

According to a second aspect of the herein disclosed subject matter, amethod of manufacturing a current sensor package is provided.

According to an embodiment, the method comprises: providing a currentpath; providing a sensing device (e.g. a sensor chip), the sensingdevice being configured for sensing a magnetic field generated by acurrent flowing through the current path, the sensing device comprisinga sensor element; positioning the sensing device spaced from the currentpath; electrically connecting the sensing device to a conductive trace;providing an encapsulant extending continuously between the current pathin the sensing device.

According to further embodiments of the first aspect, the current sensorpackage is adapted for providing the functionality of one or more of theherein disclosed embodiments and/or for providing the functionality asrequired by one or more of the herein disclosed embodiments, inparticular of the embodiments of the first and second aspect disclosedherein.

According to further embodiments of the second aspect, the method isadapted for providing the functionality of one or more of the hereindisclosed embodiments and/or for providing the functionality as requiredby one or more of the herein disclosed embodiments, in particular of theembodiments of the first and second aspect disclosed herein.

In the following, further exemplary embodiments of the herein disclosedsubject matter are described, any number and any combination of whichmay be realized in an implementation of aspects of the herein disclosedsubject matter.

In the context of the present application, the term “extendingcontinuously” may particularly denote an extension (e.g. of theencapsulant) without any internal interfaces (interfaces within theencapsulant).

In the context of the present application, the term “current sensorpackage” (or “package” for short) may particularly denote at least oneat least partially encapsulated sensor chip with at least one externalelectric contact.

The term “sensing device” may particularly denote a discrete sensorelement or a sensor chip comprising a sensor element.

The term “sensor chip” may particularly denote a chip having at leastone integrated sensor element (such as a Hall sensor or amagnetoresistive sensor), e.g. in a surface portion thereof. Accordingto an embodiment, the at least one integrated sensor element is locatedat a same main surface of the sensor chip on which the contact pad islocated. The sensor chip may be a naked die or may be already packagedor encapsulated.

In the context of the present application, the term “encapsulant” mayparticularly denote a substantially electrically insulating andpreferably thermally conductive material surrounding (for examplehermetically surrounding) the current path to provide mechanicalprotection, electrical insulation, and optionally a contribution to heatremoval during operation. Such an encapsulant can be, for example, amold compound.

In the context of the present application, the term “carrier” mayparticularly denote an electrically conductive structure which may serveas a support for the (at least one) chip. Further, the carrier may alsocontribute to an electrical connection between components and/or to anelectrical connection to a periphery, e.g. of the current sensorpackage. In other words, the carrier may fulfil a mechanical supportfunction and/or a electrical connection function.

In the context of the present application, the term “component” mayparticularly denote any electronic member which can be mounted andelectrically connected to the package to provide its function to thepackage. In particular, the component may be a passive component such asan inductor (in particular a coil), a capacitor (such as a ceramiccapacitor), an ohmic resistance, an inductance, a diode, a transformer,a sensor, etc. In particular components being not capable of controllingcurrent by another electrical signal may be denoted as passivecomponents. However, the component may also be an active component, inparticular may be a component being capable of controlling current byanother electrical signal. Active components may be an analog electronicfilter with the ability to amplify a signal or produce a power gain, anoscillator, a transistor or another integrated circuit element.

According to an embodiment, the package may be e.g. a Surface MountedDevice (SMD) or a Through Hole Device (THD).

In an embodiment, the package is configured for a working voltage in arange between 100 Volt (V) and 1000 V, e.g. for a working voltage ofabout 800 V.

The term “device” may in particular denote any device suitable forcomprising the package. In particular, according to an embodiment thedevice is a power train of an at least partially electrically drivenvehicle (e.g. an electric vehicle or a hybrid vehicle).

According to an embodiment, the package provides a high reliability andmeets safety requirements. The higher the requirements on strength andlong-term reliability of the electric insulation between the currentpath and the sensor device the more important are internal interfaces ofthe electric insulation. According to an embodiment, internal interfacesof the electric insulation are avoided, in particular internalinterfaces between the current path and the sensing device and/or thecurrent path and the conductive trace. Avoiding internal interfaces isadvantageous because along with delamination paths of internalinterfaces creepage or even clearance paths could open up which mightlead to an increased leakage current or even breakthrough. In cracks orslits in the electrical insulation discharges can appear which may leadto long-term degradation of the insulation material and in worst case toa breakthrough event.

Save insulation means highest confidence in in isolation reliability andprotection of electrical shock (e.g. caused by accidental voltagetransients). Such grade of quality is called “basic” or, for even higherdegree of withstand “reinforced”. According to the latter grade, e.g.surviving a transient voltage peak nearly at the end of a productlifetime has to be guaranteed with respect to life protection.

On the other hand, high reliability galvanic insulation is sometimesdifficult to realize with cheap standard semiconductor packagetechnology especially in low and mid voltage regions. Here, a reliablesingle layer insulation maybe advantageous. In best case, the insulationis brought from package concept and material, thereby greatly reducingthe costs. In particular, additional interlayers may rise package costsas it is the case for stacked die approaches, where a separateinsulation platelet is used for galvanic insulation purpose.

Embodiments of the herein disclosed subject matter use in encapsulantextending continuously between the current path and the sensing deviceof the current sensor package. The continuously extending encapsulantmay result in a delamination resistant insulation of the current path inthe sensing device. This in turn results in a reliable insulation in thepackage.

According to an embodiment, the encapsulant also extends continuouslybetween the current path and the conductive trace (to which the contactpath of the sensing device is electrically connected). Hence, in anembodiment the encapsulant continuously extends between the current pathon the one hand and the sensor device and its associated electricalconnections on the other hand.

According to an embodiment, the conductive trace is a carrier, inparticular a metallic carrier, further in particular a leadframe.

According to a further embodiment the sensing device is attached to thecarrier. For example, where the conductive trace is a carrier, in themethod of manufacturing the package the positioning of the sensingdevice may include attaching the sensing device to the conductive traceand the providing of the encapsulant may include providing theencapsulant continuously between the current path on the one hand andthe sensing device in the conductive trace on the other hand.

According to a further embodiment, an interconnect between the sensingdevice and the conductive trace is provided by at least one bond wireand/or at least one through silicon via (TSV).

According to an embodiment, the sensing device has a main surface andpart of the main surface is attached to the carrier whereas theremaining part of the main surface extends beyond the carrier and overthe current path. According to an embodiment, a sensor of the sensingdevice is positioned within the sensing device so as to be locatedproximate to the current path. According to an embodiment, the carrierhas an attachment portion to which the part of the main surface of thesensing device is attached. According to a further embodiment, theattachment portion of the carrier is flat.

According to an embodiment, the sensing device is attached to theencapsulant. For example, the method of manufacturing the package maycomprise providing the encapsulant over at least part of the currentpath, wherein the positioning of the sensing device includes attachingthe sensing device to the encapsulant.

For example, according to an embodiment the package comprises a pre-moldpart formed from the encapsulant. According to an embodiment, thepremold part continuously extends over at least a portion of the currentpath and between the current path and the conductive trace. According toan embodiment, the encapsulant extends over at least a portion of theconductive trace. According to an embodiment, a method of manufacturinga current sensor package comprises providing the encapsulant about thecurrent path (e.g. about part of the current path) and/or about theconductive trace (e.g. about part of the conductive trace to therebyprovide the premold part. Hence, in an embodiment the premold partcomprises the encapsulant and at least one of the current path and theconductive trace.

According to an embodiment, the sensing device is attached to thepremold part, e.g. in an attachment surface of the premold part.According to an embodiment, the encapsulant is has a recess wherein theattachment surface is provided at a bottom of the recess. In this way,walls of the recess surrounding the bottom surface provide mechanicalprotection of the sensing device. According to a further embodiment, therecess is covered with a lid and/or filled with a filling material. Thelid/filling material may provide additional protection of the sensingdevice and/or a bond wire (if present). According to an embodiment, thefilling material comprises silicone, epoxy, etc.

According to an embodiment, the sensing device is attached to theencapsulant (or, in another embodiment to the carrier) by a die attachlayer. According to an embodiment, the die attach layer is applied tothe sensing device on wafer scale. In other words, according to anembodiment, the die attach layer is applied to the wafer before dicingthe wafer into individual dies, e.g. by sawing. Typically, for a sawingprocedure the die attach layer is applied to the wafer in order toattach to wafer to a saw foil. According to an embodiment, the dieattach layer is a die attach film (DAF). Since the die attach filmusually appears better to the wafer than to the saw foil, removal of theindividual die from the saw foil leaves the die attach film remaining onthe die. In accordance with an embodiment, this die attach filmoriginating from the dicing procedure (sawing procedure) is used toattach the die (the sensing device) to the carrier or the encapsulant.According to a further embodiment, the die attach layer comprises aconductive adhesive (e.g. is a layer of conductive adhesive). Accordingto another embodiment, the die attach layer comprises a non-conductiveadhesive (e.g. is a layer of non-conductive adhesive). According to afurther embodiment, the die attach layer may comprise (or consist of) asolder, e.g. a soft solder, a hard solder, a diffusion solder, etc.

In a further embodiment, the sensing device is mounted (in particularare directly soldered, sintered or glued) to a surface of carrier or theencapsulant. In other words, the material of the solder, sinter materialand/or glue (in particular an electrically conductive glue) may be theonly material between the sensing device on the one hand and the carrieron the other hand.

According to an embodiment, the current path is formed from a leadframe.

According to an embodiment the current path and the conductive trace areinitially (i.e. in an early manufacturing stage) provided by a singleleadframe element, which comprises the current path, the conductivetrace and a connecting portion connecting the current path and theconductive trace. After providing the encapsulant over at least portionsof the current path and the conductive trace, the connecting portion maybe removed, thereby resulting in separate, electrically isolated currentpath and conductive trace. In other embodiments, any other singlecarrier (other than the leadframe element) may be used to initiallyprovide the current path and the conductive trace by a single carrier.

In an embodiment, the carrier is a metallic carrier, in particular aleadframe. In the context of the present application, the term“leadframe” may particularly denote a preferred example of a carrierbeing configured as a sheet-like metallic structure which can be punchedor patterned so as to form leadframe sections for mounting the chip(s),and connection leads as pin sections for electric connection of thepackage to an electronic environment when the chips are mounted on theleadframe. In an embodiment, the leadframe may be a metal plate (inparticular made of copper) which may be patterned, for instance bystamping or etching. Forming the carrier as a leadframe is acost-efficient and mechanically as well as electrically highlyadvantageous configuration in which a low ohmic connection of thechip(s) (and optionally other component(s)) can be combined with arobust support capability of the leadframe. Furthermore, a leadframe maycontribute to the thermal conductivity of the package and may removeheat generated during operation of the chip(s) (and, if present, thecomponent(s)) as a result of the high thermal conductivity of themetallic (in particular copper) material of the leadframe. A leadframeor any other metallic carrier may be preferred due to its simplicity.

In an embodiment, the at least one sensor chip comprises at least one ofthe group consisting of a controller circuit, a driver circuit, and asensor element. All these circuits may be integrated into onesemiconductor chip, or separately in different chips. For instance, acorresponding current sensor application may be realized by the chip(s),wherein integrated circuit elements of such a sensor chip may compriseat least one sensor element and semiconductor elements, such as atransistor (in particular a MOSFET, metal oxide semiconductor fieldeffect transistor), at least one diode, etc.

In an embodiment, the at least one sensing device is at least partiallyembedded by a separate encapsulant (i.e. a further encapsulant which maybe physically different from the encapsulant extending continuouslybetween the current path and the sensing device). In other words, twoseparate encapsulants may be provided in the package, and two separateencapsulation procedures may be carried out. For example, it is possibleto encapsulate the sensing device together with a portion of the carrierby a first encapsulant (for instance a first mold compound).Additionally, it is possible to encapsulate a part of the sensing devicewith a separate encapsulant after attaching the sensing device to thecarrier or to the first encapsulant.

In embodiment, the package comprises a common or an overall encapsulantat least partially encapsulating the carrier, the sensing device, the(first) encapsulant and the at least one component. Hence, it is alsopossible to encapsulate (in particular by a further molding procedure,more particularly an overmolding procedure) the assembled subassembliesof carrier, chip and encapsulant on the one hand and component andfurther encapsulant on the other hand by yet another encapsulant as arobust shell for mechanically protecting all constituents of thepackage.

In an embodiment, any of the (first) encapsulant and/or the separateencapsulant and/or the overall encapsulant comprises a mold compound.Hence, the respective encapsulant may comprise a mold, in particular aplastic mold. For instance, a correspondingly encapsulated component (inparticular one or more of the sensing device, the current path, and theconductive trace) may be provided by placing the component (or, moregenerally, at least one component) between an upper mold tool and alower mold tool and to inject liquid mold material therein. Aftersolidification of the mold material, formation of the encapsulant (herea mold body) is completed. If desired, the mold material may be filledwith particles improving its properties.

According to an embodiment, a support element for the conductive traceis provided before providing (e.g. injecting) the encapsulant. Accordingto a further embodiment, a support element for the current path isprovided before providing (e.g. injecting) the encapsulant. The supportelement(s) may prevent or at least reduce a deformation of thecorresponding supported element (i.e. the conductive trace or thecurrent path) due to the providing (e.g. injecting) of the encapsulant.

According to a further embodiment, the support element is removed afterproviding the encapsulant over at least part of the support element andthe corresponding supported element (i.e. the conductive trace or thecurrent path). In particular, according to an embodiment the supportelement is removed after solidification of the encapsulant (e.g. themold material). Removal of the support element results in a hole in theencapsulant. According to an embodiment, the hole in the encapsulant isfilled with an electrically insulating filling material.

According to an embodiment, the encapsulant comprises a hole, inparticular a hole exposing the conductive trace. According to a furtherembodiment, the encapsulant comprises a hole exposing the current path.According to a further embodiment, the hole (i.e. the at least one hole)is filled with an electrically insulating filling material.

According to an embodiment, the package further comprising a mountingside which is configured to be mounted to a support (e.g. a printedcircuit board (PCB) or a direct copper bonding (DCB)). According to afurther embodiment, the sensor element faces away from the mounting sideand/or facing away from the current path. According to a furtherembodiment, positioning the sensing device comprises positioning thesensor element facing away from the mounting side and/or facing awayfrom the current path.

According to another embodiment, the support is a printed circuit board(PCB). Thus, the support may be in particular manufactured on the basisof resin (in particular epoxy resin), if desired mixed with particles(such as fibers, for instance glass fibers). Suitable dielectricmaterials for the PCB are e.g. prepreg or FR4. A suitable electricallyconductive material for the PCB is copper.

According to an embodiment, the support is a layered structurecomprising a ceramic part and a metal part. For example, according to anembodiment the support is a direct copper bonding (DCB) comprising aceramic plate and copper layers bonded to one side thereof (or twoopposing sides thereof). Bonding between the copper layer and theceramic plate may be provided by a copper-oxygen eutectic which formsbonds between the copper layer and the ceramic plate. The copper-oxygeneutectic may be formed by heating the copper layer and the ceramic plateto controlled temperature in an atmosphere of nitrogen containing anamount of 20-40 ppm of oxygen. The copper layer bonded to the ceramicmay be shaped into a pattern (e.g. the copper layer may be preformed(e.g. stamped) before the bonding to the ceramic plate or may bestructured (e.g. by etching). According to an embodiment, the formationof the copper layer on the ceramic plate comprises applying a seed layerand plating the seed layer. The ceramic material may comprise forexample one or more of alumina (Al2O3), aluminum nitride (AlN) orberyllium oxide (BeO). the copper layers may have a thickness in a rangebetween 200 micrometer (μm) and 300 μm and may be plated, e.g. withnickel, a nickel alloy, aluminum nickel or aluminum.

According to an embodiment, the conductive trace comprising an first endportion and the current path comprising a second end portion, whereinthe first and second end portions define a distance (minimum spacing)between the conductive trace and the current path. According to afurther embodiment, the first end portion, the second end portion andthe sensing device are located at different levels in a directionperpendicular to a main surface of the sensing device. According to anembodiment, the first end portion is located at a level between thesensing device and the second end portion. According to a furtherembodiment the second end portion is located at a level between thesensing device and the first end portion.

According to a further embodiment, the first end portion is located at alevel below the sensing device, e.g. at a level between the sensingdevice and the current path. In this application, the term “level” mayin particular denote a distance from a bottom surface of the package.According to a further embodiment, the first end portion is located atthe level below the current path.

According to an embodiment, the conductive trace comprises a raisedportion being spaced from the sensing device. For example, the first endportion may be located at a level below the level of the raised portion.This allows for the raised portion to be exposed from the encapsulantwhile at the first end portion is located within the encapsulant. Thismay allow for a secure attachment of the conductive trace in theencapsulant.

According to an embodiment, the relative positions of the current pathin the conductive trace are determined by the three dimensional shape ofthe respective leadframe portion. The shape of the respective leadframeportion may be obtained by bending the leadframe.

According to an embodiment, the package further comprises a bond wireelectrically connecting the conductive trace and the contact pad.Accordingly, in the method of manufacturing the package the electricallyconnecting of the contact pad to the conductive trace may compriseproviding a bond wire between the contact pad and the conductive trace.

A bond wire may have the shape of a round filament or the shape of aflat ribbon, so that the bond wire may also be configured as a bondribbon. Establishing a connection by one or more bond wires is a simpleprocedure which may implement bond wires made of copper and/or aluminum.

Other electrical connections are also possible, depending on thegeometry of the conductive trace with respect to the contact pad.

According to an embodiment, the current path is at least partiallysurrounded by the encapsulant.

According to a further embodiment, the current path comprises an exposedportion forming part of an outer surface of the package. In other words,according to an embodiment a leadframe forming the current path may beshaped as an exposed pad.

According to an embodiment, the sensing device comprises at least oneHall sensor, in particular at least two Hall sensors.

According to a further embodiment, the sensing device comprises at leastone magnetoresistance sensor, in particular at least twomagnetoresistance sensors.

Two or more sensors (Hall sensors and/or magnetoresistance sensors)provide the advantage that the signals thereof may be combined so as toprovide a differential signal from which an influence of externalmagnetic fields (which are not related to the current to be measured andwhich are undesired) is removed or at least reduced.

According to an embodiment, the current path is electrically connectedto a first set of contact pins; the conductive trace being electricallyconnected to a contact pin of a second set of contact pins; and thefirst set of contact pins and the second set of contact pins are locatedon opposite sides of the package. Such a geometry of contact pins mayfacilitate the electrical insulation of the current path and theelectrical connection to the sensing device.

The current path may have any geometry suitable for providing anappropriate current density and hence an appropriate magnetic field forthe sensor device.

According to an embodiment, the current path comprises a measurementportion of reduced cross-section; the measurement portion extendingbetween two spaced apart side portions (of the current path). Accordingto an embodiment, the measurement portion is a straight portion of thecurrent path. This may facilitate providing the measurement portion withdefined dimensions.

According to an embodiment, the side portions have a thermal mass whichis larger than the thermal mass of the straight portion, in particularby a factor of at least two, e.g. at least four or at least six.According to an embodiment, each side portion is electrically connectedto one or more leads (which in an embodiment are also formed from theleadframe, from which the measurement portion and the side portions areformed). The relatively large thermal mass of the side portions improvesremoval of thermal energy from the measurement portion which in turnallows a higher current density and hence a better sensitivity of thecurrent sensor package.

According to an embodiment, a length of the measurement portion betweenthe side portions is smaller than a width of the measurement portionperpendicular to the length. In other words, the length of themeasurement portion corresponds to the distance of the site portionswhich is bridged by the measurement portion. For example, a ratio of thelength of the measurement portion over its width is in a range between0.5 and 0.95 and is e.g. 0.75.

According to an embodiment, at least one of the side portions, e.g. eachside portion comprises a through hole. Due to the relatively largesurface area of the site portions, such a through hole may reduce orprevent the formation of voids in the encapsulant and/or may improve thestructural integrity of the combination of the side portions and theencapsulant. The above and other objects, features and advantages of thepresent invention will become apparent from the following descriptionand the appended claims, taken in conjunction with the accompanyingdrawings.

DETAILED DESCRIPTION

The illustration in the drawings is schematically and not to scale. Inthe drawings, similar elements or functionality similar elements aredenoted by the same reference signs or by reference signs which differfrom each other only within the first digit. In order to avoidunnecessary repetitions, the description of such a similar elements isnot repeated in subsequent figures.

FIG. 1 illustrates a cross-sectional view of a current sensor package100 according to embodiments of the herein disclosed subject matter.

According to an embodiment, the package 100 comprises a current path102, e.g. a current rail. In accordance with a further embodiment, thepackage 100 comprises a sensing device 104. According to an embodiment,the sensor device 104 is a sensor chip comprising at least one sensorelement, e.g. two sensor elements 106, e.g. two Hall sensors or twomagnetoresistance sensors. According to an embodiment, the sensingdevice 104 comprises a first main surface 105 wherein the at least onesensor element 106 is located in or close to the first main surface 105.In accordance with an embodiment, the first main surface 105 faces awayfrom the current path 102. In other words, in accordance with anembodiment, the at least one sensor element 106 faces away from thecurrent path 102.

According to an embodiment, the sensing device 104 is spaced from thecurrent path 102 by a distance 108. The sensing device 104 comprises acontact pad 110 which faces away from the current path 102, e.g. asshown in FIG. 1. The contact pad 110 is electrically connected to aconductive trace 112 by a bond wire 114. In accordance with anembodiment, the conductive trace 112 is a sensor pin, e.g. as shown inFIG. 1.

According to a further embodiment, the package 100 comprises anencapsulant 116 extending continuously without internal interfacesbetween the current path 102 and the sensing device 104. In accordancewith an embodiment, the encapsulant 116, the current path 102 and theconductive trace 112 form part of a premold part two which the sensingdevice may be attached in a separate manufacturing step (e.g. aftercuring the encapsulant 116).

In accordance with an embodiment, the encapsulant 116 extending betweenthe current path 102 and the sensing device 104 electrically isolatesthe high voltage potential at the current path 102 from the low voltagepotential at the conductive trace 112.

According to an embodiment, the conductive trace 112 comprises a firstend portion 118 and the current path 102 comprises a second end portion119 which end portions defines a distance 120 between the conductivetrace 112 and the current path 102. In accordance with an embodiment,the first end portion 118 is located at a level 122 which is below thesensing device 104. In other words, the first end portion 118 is spacedfrom a lower main surface 124 of the sensing device 104.

According to an embodiment, the second end portion 119 of the currentpath 102 is located at a level 126 between the sensing device 104 andthe first end portion 118. In other words, the second end portion 119 ofthe current path 102 is spaced from the lower main surface 124 by thedistance 108 and the first end portion 118 is spaced from the lower mainsurface 124 by a further distance 128 which is larger than the distance108.

According to an embodiment, the conductive trace 112 comprises a raisedportion 130 which is spaced from the sensing device 104. In accordancewith an embodiment, the bond wire 114 is bonded to the conductive trace112 at the raised portion 130 in a contact region 132. According to anembodiment, the raised portion 130 is exposed with respect to theencapsulant 116 in the contact region 132.

According to an embodiment, the current path 102 is connected to a firstset of contact pins 134 extending out of the package 100. According to afurther embodiment, the conductive trace 112 is electrically connectedto a contact pin of a second set of contact pins 136 extending out ofthe package 100. In accordance with an embodiment, the first set ofcontact pins 134 and the second set of contact pins 136 are located onopposite sides of the package 100, e.g. as shown in FIG. 1.

According to an embodiment, the encapsulant 116 comprises a hole 138exposing the conductive trace 112. In accordance with an embodiment, thehole 138 arises from a support pin (not shown in FIG. 1) which supportedthe conductive trace 112 during forming the encapsulant 116, inparticular during forming the encapsulant 116 between the current path102 and the conductive trace 112. In accordance with an embodiment, thehole 138 is filled with an electrically insulating filling material 139such as e.g. silicone, epoxy, etc. In accordance with an embodiment, thehole 138 is located at the position such that an interface 140 betweenthe encapsulant 116 and the filling material 139 is not located betweenthe current path 102 and the sensing device 104 or between the currentpath 102 and the conductive trace 112.

According to a further embodiment, the encapsulant 116 comprises a hole142 exposing the current path 102. In accordance with an embodiment, thehole 142 arises from a support pin (not shown in FIG. 1) which supportedthe current path 102 during forming the encapsulant 116, in particularduring forming the encapsulant 116 between the current path 102 and thesensing device 104. In accordance with an embodiment, the hole 142 isfilled with an electrically insulating filling material 144 such as e.g.silicone, epoxy, etc. In accordance with an embodiment, the hole 142 islocated at the position such that an interface 146 between theencapsulant 116 and the filling material 139 is not located between thecurrent path 102 and the sensing device 104 or between the current path102 and the conductive trace 112.

In accordance with an embodiment, the sensing device 104 is attached toan attachment surface 148 of the encapsulant 116 e.g. by means of a dieattach layer 150, e.g. a die attach film. According to an embodiment,the encapsulant has shaped therein a recess 152 in which the sensingdevice 104 and the bond wire 114 are located. In accordance with anembodiment, the recess 152 is filled with an insulating filling material154 such as epoxy, silicone, etc. According to an embodiment, theinsulating filling material 154 may be provided for protection of thesensing device 104 and/or the bond wire 114. In accordance with anembodiment, the sensing device 104 is at least partially enclosed by theencapsulant 116 (mold body).

In accordance with an embodiment, a lid 156 may be provided to close therecess 152.

Further, FIG. 1 illustrates some isolation aspects according toembodiments of the herein disclosed subject matter. In particular, FIG.1 further illustrates in particular the distances 108, 120 between ahigh voltage side 160 (comprising in particular the current path 102) onthe one and a supply voltage side 162 (low voltage side, comprising inparticular the conductive trace 112, the bond wire 114 and the sensingdevice 104) on the other hand.

Further illustrated in FIG. 1 is the creepage/clearance distance 164between exposed portions of the high-voltage side 160 (in particular ofthe current path 102) and the low voltage side 162 (in particular theconductive trace 112). Accordingly and in accordance with an embodiment,creepage may occur along an outer surface of the current sensor packagebut not along interfaces within the current sensor package (e.g.interfaces within the encapsulant (116), as such interfaces are avoided(as far as possible/suitable)). In an embodiment at least interfacesbetween the current path 102 and the conductive trace 112 and betweenthe current path 102 and the sensing device 104 are avoided (i.e. inthese regions the encapsulant 116 is free of interfaces).

In accordance with a further embodiment, the current sensor package 300comprises a mounting side 163 which is configured to be mounted to asupport, e.g. a printed circuit board, a direct copper bonding, etc. Inaccordance with an embodiment, the sensor element 106 faces/main surface105 faces away from the mounting side 163.

FIG. 2 illustrates a cross-sectional view of a further current sensorpackage 200 according to embodiments of the herein disclosed subjectmatter.

In the description of FIG. 2, a repetition of the description ofelements which are similar or identical two elements of FIG. 1 isavoided. The description of such elements provided with regard to FIG. 1is valid also for FIG. 2.

In accordance with an embodiment, the conductive trace 112 is a carrieror part of a carrier and is in particular a lead finger of a leadframe.In accordance with a further embodiment, the sensing device 104 isattached at least partially to the conductive trace 112, e.g. by a dieattach layer 150. In particular, according to an embodiment the sensingdevice 104 extends beyond the conductive trace 112, the thus having afree end 151 which is located over the current path 102 (about spacedfrom the current path 102). According to a further embodiment, not shownin FIG. 2, the current path 102 is exposed and forms a part of a surfaceof the package 200.

Instead of a bond wire 114, which electrically connects the contact pad110 and the conductive trace 112, a through silicon via, extendingthrough the sensing device 104, may be provided (not shown in FIG. 2).

In accordance with an embodiment, the encapsulant 116 is provided afterpositioning of the current path 102, the sensing device 104 and theconductive trace 118 and after electrically connecting the sensingdevice 104 with the conductive trace 118. In accordance with anembodiment, the encapsulant 116 is a mold body as shown in FIG. 2.

In accordance with a further embodiment, the first end portion 118 ofthe conductive trace 112 is located at a level between the sensingdevice 104 and the second end portion 119, e.g. as shown in FIG. 2.

FIG. 3 illustrates a cross-sectional view of a further current sensorpackage 300 according to embodiments of the herein disclosed subjectmatter.

The current sensor package 300 is similar to the current sensor package200 of FIG. 2 but the first with respect to the location of the sensingdevice 104. In particular, according to an embodiment the conductivetrace 112 comprises two opposing first and second sides 158, 159 whereinthe sensing device 104 is attached to the first side 158 of theconductive trace 112 and the bond wire 114 is attached to the secondside 159 of the conductive trace 112, e.g. as shown in FIG. 3. It isnoted, that in contrast to this embodiment, in the current sensorpackage 200 of FIG. 2 both the sensing device 104 and the bond wire 114are attached to the same side of the conductive trace 112.

In accordance with an embodiment, the end portion 118 of the conductivetrace 112 is located at the level between the end portion 119 of thecurrent path 102 and the sensing device 104, e.g. as shown in FIG. 3.

In accordance with a further embodiment, the encapsulant 116 is free ofany holes exposing the conductive trace 112 or the current path 102. Inother words, according to an embodiment the encapsulant 116 does notcomprise holes 138, 142 as described with regard to FIG. 1.

In accordance with an embodiment, the first main surface 105 of thesensing device 104 (or differently said, the at least one sensor element106) faces towards the current path 102. In accordance with a furtherembodiment, the at least one sensor element 106 faces away from themounting side 163 of the current sensor package 300. The mounting side163 is configured to be mounted on a support 165.

FIG. 4 illustrates a cross-sectional view of a further current sensorpackage 400 according to embodiments of the herein disclosed subjectmatter.

In the description of FIG. 4, a repetition of the description ofelements which are similar or identical two elements of FIG. 1 isavoided. The description of such elements provided with regard to FIG. 1is valid also for FIG. 4.

In accordance with an embodiment, the current path 102 comprises anexposed portion 166 forming part of an outer surface 168 of the package400.

FIG. 5 to FIG. 10 illustrate different geometries of a current path 102(current rail) according to embodiments of the herein disclosed subjectmatter.

FIG. 5 illustrates an exemplary first geometry 170 of a current path102.

In accordance with an embodiment, the current path 102 is a currentrail. In accordance with an embodiment, the current path 102 comprises ameasurement portion 172, wherein the measurement portion has a reducedcross-section. In other words, if the thickness of the current path isapproximately constant the different cross-section at differentpositions of the current path can be estimated by the different lateraldimension of the current path. In accordance with a further embodiment,the current path 102 comprises two spaced apart side portions 174. Inaccordance with a further embodiment, the measurement portion 172extends between the two side portions 174.

According to an embodiment, the measurement portion 172 is a straightportion of the current path 102. According to a further embodiment, theside portions 174 have a thermal mass which is larger than the thermalmass of the straight portion in particular by a factor of at least two,e.g. as shown in FIG. 5. According to an embodiment, each side portion174 is connected to one or more leads 176, e.g. one lead 176 as shown inFIG. 5. Accordingly, in an embodiment each side portion 174 is delimitedby the measurement portion 172 and the lead 176. According to anembodiment, a length 178 of the measurement portion 172 between the sideportions 174 is smaller than a width 180 of the measurement portionperpendicular to the length 178. For example, according to an embodimentthe length 178 is about 300 μm, the width 180 is about 400 μm and theentire length 179 of the current path 102 is 4.56 mm.

FIG. 6 illustrates an exemplary second geometry 270 of a current path102.

In accordance with an embodiment, each side portion 174 comprises athrough hole 182, e.g. as shown in FIG. 6. According to an embodiment,the through hole 182 has a triangular shape, as shown in FIG. 6.

FIG. 7 illustrates an exemplary third geometry 370 of a current path102.

The third geometry 370 is similar to the first geometry 170 of FIG. 5.According to an embodiment, each side portion is connected to two leads176, e.g. as shown in FIG. 7.

FIG. 8 illustrates an exemplary fourth geometry 470 of a current path102.

The fourth geometry 470 is similar to the first geometry 170 and thirdgeometry 370. According to an embodiment, each side portion 174 iselectrically connected to one lead 176 which has a width similar to themaximum width of the side portion 174, e.g. as shown in FIG. 8. Forexample, according to an embodiment, a maximum width of the lead 176 isin the range of about 80% to 120% of the maximum width of the sideportion 174. Further in accordance with an embodiment, a through hole184 is formed in the lead 176.

FIG. 9 illustrates an exemplary fifth geometry 570 of a current path102.

The fifth geometry 570 is similar to the third geometry 370 of FIG. 7.According to an embodiment, a through hole 182 is formed in the siteportions 174, e.g. as shown in FIG. 9. According to an embodiment, thethrough hole has a circular shape, e.g. as shown in FIG. 9.

FIG. 10 illustrates an exemplary sixth geometry 670 of a current path102.

In accordance with an embodiment, the side portions 174 have a generallyrectangular shape.

In summary, having regard to FIG. 5 to FIG. 10, according to anembodiment, the shape of the site portions tapers in a direction fromthe lead 176 to the measurement portion 172 and has a general triangularshape, e.g. as shown in FIGS. 5, 7, 8 and 9. According to an embodimenteach side portion has in a direction from the lead 176 to themeasurement portion 172 a first part of increasing cross-section and asecond part of the increasing cross-section, e.g. as shown in FIGS. 5,6, 7, 8 and 9. According to a further embodiment, a distance betweenopposing side portions 174 of the current rail 102 changes from a firstdistance 186 (see FIG. 10) of opposing leads 176 to the length 178 ofthe measurement portion 172, in particular in a stepwise manner, e.g. asshown in FIG. 5 to FIG. 10.

FIG. 11 shows the exemplary second geometry 270 of the current path 102of FIG. 6 and illustrates a possible location for two Hall sensors 188.

According to an embodiment, a first Hall sensor 188 is located betweenthe two side portions 174 proximate to (e.g. besides) the measurementportion 172. According to an embodiment, a second Hall sensor 188 islocated opposite the first Hall sensor 188 with the measurement portion172 extending between the two or sensors 188, e.g. as shown in FIG. 11.

FIG. 12 shows the exemplary second geometry 270 of the current path 102of FIG. 6 and illustrates a possible location for two magnetoresistancesensors 190.

According to an embodiment, the current path 102 comprises a slit 192between the two side portions 174. According to an embodiment, a firstmagnetoresistance sensor 190 is located between the slit 192 and theopening 182 of one of the two side portions 174 and a secondmagnetoresistance sensor 190 is located between the slit 192 and theopening 182 of the other of the two side portions 174, e.g. as shown inFIG. 12.

FIG. 13 illustrates perspective view of a leadframe 194 according toembodiments of the herein disclosed subject matter.

According to an embodiment, the leadframe 194 comprises the current path102, four conductive traces 112 and a connecting portion 196 connectingthe current path 102 and the conductive traces 112. After manufacturingthe current sensor package 100 according to embodiments of the hereindisclosed subject matter on the basis of the leadframe 194, the firstset of contact pins 134 (i.e. the leads 176 of the current path 102) andthe second set of contact pins 136 (compare also FIG. 1) are separatedfrom the connecting portion 196.

It should be noted that the term “comprising” does not exclude otherelements or features and the “a” or “an” does not exclude a plurality.Also elements described in association with different embodiments may becombined. It should also be noted that reference signs shall not beconstrued as limiting the scope of the claims. Moreover, the scope ofthe present application is not intended to be limited to the particularembodiments of the process, machine, manufacture, composition of matter,means, methods and steps described in the specification. Accordingly,the appended claims are intended to include within their scope suchprocesses, machines, manufacture, compositions of matter, means,methods, or steps.

What is claimed is:
 1. A current sensor package, comprising: a currentpath; a sensing device, in particular a sensor chip, the sensing devicebeing spaced from the current path, and the sensing device beingconfigured for sensing a magnetic field generated by a current flowingthrough the current path; the sensing device comprising a sensorelement, the sensing device being electrically connected to a conductivetrace; a mounting side which is configured to be mounted to a support;an encapsulant extending continuously between the current path and thesensing device and between the current path and the mounting side wherethe sensing device extends over the current path; the encapsulantextending continuously between the current path and the conductivetrace; and the sensing device being attached to the encapsulant.
 2. Thepackage according to claim 1, the conductive trace being a carrier, inparticular a leadframe.
 3. The package according to claim 1, the currentpath is formed form a metallic carrier, in particular a leadframe. 4.The package according to claim 1, the encapsulant comprising a holeexposing the conductive trace, the hole being filled with anelectrically insulating filling material.
 5. The package according toclaim 1, the conductive trace comprising a first end portion and thecurrent path comprising a second end portion wherein the first andsecond end portions define a distance between the conductive trace andthe current path, wherein the first end portion, the second end portionand the sensing device are located at different levels in a directionperpendicular to a main surface of the sensing device; in particularwherein the first end portion is located at a level between the sensingdevice and the second end portion or wherein the second end portion islocated at a level between the sensing device and the first end portion.6. The package according to claim 5, the conductive trace comprising araised portion being spaced from the sensing device.
 7. The packageaccording to claim 1, the sensing device further comprising a contactpad and the package further comprising a bond wire electricallyconnecting the conductive trace and the contact pad.
 8. The packageaccording to claim 1, wherein the current path comprises an exposedportion forming part of an outer surface of the package.
 9. The packageaccording to claim 1, wherein the sensing device comprises at least onefurther sensor element.
 10. The package according to claim 1, whereinthe sensor element of the sensing device is one of a Hall sensor, and amagnetoresistance sensor, in particular wherein the magnetoresistancesensor is an anisotropic magnetoresistance sensor, a giantmagnetoresistance sensor, a colossal magnetoresistance sensor, or atunnel-magnetoresistance sensor.
 11. The package according to claim 1,the current path being electrically connected to a first set of contactpins; the conductive trace being electrically connected to a contact pinof a second set of contact pins; and the first set of contact pins andthe second set of contact pins being located on opposite sides of thepackage.
 12. The package according to claim 1, the current pathcomprising a measurement portion of reduced cross-section; themeasurement portion extending between two spaced apart side portions; inparticular wherein the measurement portion is a straight portion of thecurrent path; in particular wherein the side portions have a thermalmass which is larger than the thermal mass of the straight portion, inparticular by a factor of at least two.
 13. The package according toclaim 12, wherein a length of the measurement portion between the sideportions is smaller than a width of the measurement portionperpendicular to the length.
 14. The package according to claim 12,wherein each side portion comprises a through hole.
 15. The packageaccording to claim 1, wherein the encapsulant, the conductive trace; andthe current path form part of a premold part, in particular wherein thepremold part comprises an attachment surface and the sensing device isattached to the attachment surface.
 16. The package according to claim1, the sensor element facing away from the mounting side and/or facingaway from the current path.